hey guys, my 1999 sierra half ton has a real bad squeak. i thought it was the idler pulley but i just changed that and still the squeak. does anyone know what the smooth, shinny pulley in the top middle is called? its a 4.3L RWD with NO A/C. i'll try that next.
oh yea, this is weird...i sprayed the belt with fluid film by mistake trying to hit where a pulley spins and the squeak stopped for a minute but then started again.

How does the belt look? Have you checked at www.rockauto.com Should be able to locate a pulley there.

I think the top center (not ribbed) is also an idler.

top left - alternator
top middle - idler (smooth)
top right - idler (ribbed)
middle left - tensioner
middle middle - water pump
middle right - power steering
lower middle - crankshaft

Does that sound right?

You might want to pull the belt and manually spin all the pullies. My guess is your water pump is squeaking, but that'* because that is what happened on two of my cars recently.

Make sure its not the belt slipping and making the sound you hear.

thanks, i thought it was called an idler and with my luck it will be the pump.

If it is the water pump, it is a an easy change on that engine. The water pump just bolts on the engine, and you don't have to tear the front end of the engine apart to get at it. This link tells you how, and even provides a picture by picture walk through of how to do it.

http://wiki.answers.com/Q/How_do_you..._to_be_removed

hey thanks.

hey you're welcome.

update: i haven't changed anything and the squeak has stopped completely. now, a while back, just before the squeak...i blew the gasket out of the oil filter and covered everything with oil including the serpentine belt. do you think this would have caused the squeak until the oil was completely gone off the belt?
not a sign of a squeak now and everything is working normal.
i have often said GMC'* are half human and can heal them selfs but can that be true. lol

Oil on the belt would cause a squeak. Perhaps that'* all it was.

thanks bud, im almost convinced thats all it was. damn, this is a great site.